RADIOLOGY: AORTA: Case# 19: ASCENDING & DESCENDING AORTIC ANEURYSM. 71 year old female with follow up case of thoracoabdominal aortic aneurysm now presented with abdominal and back pain, hypertension and tachycardia. An aortic arch aneurysm extends down to the level of the left pulmonary artery which measures 9 x 8 cm in its maximum AP and transverse dimension. There is a large amount of peripherally-located mural thrombus within this aneurysm. There is enlarging hematoma in the middle mediastinum which displaces the adjacent airway, esophagus and pulmonary artery. The hematoma has an attenuation value of 80 to 90 HU. A second aneurysm of the descending thoracic aorta extends downward below the diaphragm to just above the left renal vein. The aneurysm abuts and displaces the stomach which contains slightly high attenuation fluid which may represent poorly mixed oral contrast or blood clot. CT signs of aortic aneurysm include aortic dilatation and deformity, thickened aortic wall, calcification (peripheral or within a thrombus), and mural thrombus (crescentic or circumferential). A dynamic CT scan can demonstrate the proximal and distal extent of the aneurysm as well as the potential complications of the aneurysm, such as periaortic/mediastinal hematoma. If a mediastinal hematoma ia accompanied by high attenuation pleural or pericardial fluid, a leaking aneurysm must be suspected.